Brandon J. Smith, MD, PharmD: Don't Go Chasing Mycobacteria

At the Making a Difference in Infectious Diseases 2019 (MAD-ID) annual meeting, Brandon J. Smith, MD, PharmD, PGY3 Internal Medicine Resident and the Resident Chair of the Antimicrobial Stewardship Program, at UPMC Mercy, presented a poster detailing the case of a patient who presented to the hospital with generalized pain and a thigh abscess. Upon the completion of scans, ground-glass opacity was found in her lung, leading the emergency department staff to suspect a mycobacterial infection.

In an exclusive interview with Contagion®, Smith discussed the case and highlighted his key takeaways and lessons learned from the case.

Interview transcript (modified slightly for readability):

Contagion®: Can you describe the case described in your poster of the patient treated for mycobacterial infection?

Smith: This was a very interesting case that I encountered when I was actually admitting residents to the medical ICU overnight several months ago. We had a patient that came into our emergency department in her 30s, was an IV drug abuser, and was the unfortunate victim of a sexual assault a few days previously. As part of her work up in the emergency department, they did trauma scans and basically CTed her entire body and 1 of the things that was found was some ground-glass opacity in her lung that was read as possibly mycobacterial infection versus necrotizing bacterial pneumonia. Of note, when the patient presented she was actually presenting for just generalized pain and a thigh abscess, she did not report any of the symptoms we think of with mycobacterial infection such as prolonged cough, fevers, chills, night sweats, and her presentation was much more classic with an IV drug abuser that has a Staph aureus infection. However, our emergency department anchored on this finding of possible mycobacterial infection and while appropriately placing in the patient into airborne isolation to rule out TB, they also decided to empirically start on anti-tuberculosis medicines upfront and in addition to starting on appropriate antibacterial therapy, cefepime, and vancomycin, to cover for more common infections. So, in our patient’s case, she ended up with a MRSA bacteremia, which explained the abscesses as well as the necrotizing pneumonia that was a result of the MRSA infection. Thankfully, we were able to discontinue the anti-tuberculosis medications and she only received a single dose of each of those agents, which we were able to minimize the toxicity that can be associated with because those are by no means benign medications. So, it was one of the stewardship efforts to try to minimize inappropriate antimicrobials.

Contagion®: How can incorrect diagnoses such as this one be avoided?

Smith: I think whenever patients are presenting we need to keep a couple of factors in mind when making our diagnoses. One is to do our best to keep an open mind to different diagnoses, which I agree with the ED, to definitely in this case, keep mycobacterial infection within the differential, but we also need to be treating and focusing on what the common etiologies and pathogens are. In a patient with significant risk factors for TB and many more risk factors for a Staph aureus infection, try to focus our efforts there and then use our diagnostic tests to help guide us. One of my co-residents actually has a poster [at MAD-ID 2019] on a similar case where that procedure was followed through a little more and the diagnostic tests did discover tuberculosis in a patient, but antimicrobial therapy was continued more appropriately until the diagnosis was reached.

Contagion®: What do you think are the lessons that were learned from this case?

Smith: So, I think the most important lesson that can be learned is to really focus on trying to collect all of your data that you possibly can, whether that’s cultured data or using other clinical markers to aid in your decision making.

The poster, “Don’t Go Chasing Mycobacteria, Please Stick to the Staphylococcus Aureus That You’re Used To,” was presented on Thursday, May 9, 2019, at MAD-ID 2019 in Orlando, Florida.